Sky-blue Aster
Symphyotrichum oolentangiense
Species Identification
Information needed to identify the plant in the field
Native-MIFlora:
Native
Duration:
perennial
Height:
2'-3'
Stature:
Knee
Bloom Color:
Purple
Compact Bloom Range:
SEP - OCT
Light:
Sn
Moisture:
D, M
Michigan Flora Description:
Aster oolentangiensis of Michigan Flora . Savannas of oak (with hickory, sassafras, and/or pine, jack pine in Clare Co.); dry open sandy ground as well as moister prairies. The relatively broad phyllaries and usually strongly scabrous upper surfaces of the leaves will distinguish this species from others with which it might be confused.
Germination Ecology / Real-World Behavior:(ⓘ Prompt)
Sky Blue Aster seeds mature and disperse in fall, equipped with small tufts of hair that allow wind dispersal to new locations. The species produces abundant seeds when healthy, though germination can be finicky and prefers cool soil conditions. Seeds do not require cold stratification but benefit from fall planting or dormant seeding, allowing natural winter conditioning to break dormancy. Germination typically occurs the following spring after seeds experience cool, moist conditions through winter weathering.
Based on genus patterns: Seeds disperse in late fall through winter via wind-carried pappus, with peak dispersal occurring after seed heads dry and open. Based on family patterns: Seeds exhibit physiological dormancy typical of Asteraceae, requiring cold-moist stratification to break dormancy mechanisms. Based on genus patterns: Natural germination occurs primarily in spring following winter stratification, with seedlings emerging as soil temperatures warm in late spring to early summer. Based on general practice: Light often enhances germination rates, and seeds may show variable dormancy depth requiring 30-90 days of cold treatment for uniform germination.
Habitat Notes:(ⓘ Prompt)
Sky-blue aster grows in oak savannas alongside hickory, sassafras, and pine, as well as on dry open sandy ground and in moister prairies throughout Michigan. In Southeast Michigan, it's found in well-drained soils of dry and mesic prairies and savannas. The seeds have fluffy white tufts (pappus) that allow wind to efficiently carry them over long distances for dispersal. When mature, the fluffy seeds are released from the flower heads and drift on air currents to establish new populations in suitable habitat.
Sky-blue aster also thrives in hill prairies, rocky upland woodlands, limestone glades, and sandy meadows, showing adaptability to both mesic and dry conditions across various soil types including loamy, sandy, rocky, or clay soils. The species is typically found in higher quality natural areas where original ground flora remains intact and benefits from occasional wildfires or disturbance that reduces woody competition. The small bullet-shaped seeds (achenes) are about 2mm long with hair tufts at their tips, designed for efficient wind dispersal to colonize new suitable habitat.
Based on species patterns: Symphyotrichum oolentangiense typically grows in wetland margins, wet prairies, and moist disturbed areas including ditches and low-lying fields. Based on genus patterns: Plants prefer full sun to partial shade with consistent soil moisture through the growing season. Based on family patterns: Seeds are small achenes topped with white pappus (fluffy bristles) that enable wind dispersal in late fall through early winter. The pappus acts like tiny parachutes, allowing seeds to drift considerable distances from parent plants and accumulate in sheltered areas or against vegetation barriers.
BONAP Range Map:
SE Michigan Monthly Observations:
Previously Known As:
Aster azureus, Aster capillaceus, Aster capillaceus, Aster capillaris, Aster oolentangiensis
Common Names:
sky blue aster, azure aster, skyblue aster
Coefficient of Conservatism (C):
4.0
— Prefers natural areas
This plant does best in natural areas but can handle some changes to its environment. Finding it suggests the habitat is in decent shape.
Explained
Coefficient of Wetness (CW):
5.0
— Needs dry ground
This plant almost never grows in wetlands. It needs well-drained soil and can rot in soggy conditions.
Explained
Similar Species / Distinguishing Features:(ⓘ Prompt)
• Native — Short's Aster (Symphyotrichum shortii) is most similar, with heart-shaped leaves and blue-violet flowers, but has hairy flower bracts (phyllaries) and narrowly heart-shaped leaves extending higher up the stem, while Sky Blue Aster's heart-shaped leaves are mainly at the base.
• Native — Smooth Blue Aster (Symphyotrichum laeve) has blue flowers but all leaves lack stalks (sessile), while Sky Blue Aster has stalked lower and middle leaves.
• Native — Blue Wood Aster (Symphyotrichum cordifolium) has heart-shaped leaves but prefers woodland habitats and has distinctly toothed leaf margins.
• Native — Arrowleaf Aster (Symphyotrichum urophyllum) has similar heart-shaped lower leaves with winged stalks but produces white flowers instead of blue.
• Native — Smooth Blue Aster (Symphyotrichum laeve) has blue flowers but all leaves lack stalks (sessile), while Sky Blue Aster has stalked lower and middle leaves.
• Native — Blue Wood Aster (Symphyotrichum cordifolium) has heart-shaped leaves but prefers woodland habitats and has distinctly toothed leaf margins.
• Native — Arrowleaf Aster (Symphyotrichum urophyllum) has similar heart-shaped lower leaves with winged stalks but produces white flowers instead of blue.
• Based on genus patterns:
• Native — Symphyotrichum laeve (smooth blue aster) differs by having distinctly clasping stem leaves and typically smoother, more glaucous foliage.
• Native — Symphyotrichum ericoides (white oldfield aster) has much smaller, more numerous white flowers and needle-like leaves.
• Native — Symphyotrichum pilosum (frost aster) typically has smaller white flowers and more densely hairy stems and leaves.
• Native — Symphyotrichum novae-angliae (New England aster) has larger purple flowers and distinctly clasping, hairy leaves. Based on family patterns:
• Native — Eurybia species (formerly Aster) can be distinguished by their broader, more heart-shaped basal leaves and typically earlier bloom times.
• Native — Symphyotrichum laeve (smooth blue aster) differs by having distinctly clasping stem leaves and typically smoother, more glaucous foliage.
• Native — Symphyotrichum ericoides (white oldfield aster) has much smaller, more numerous white flowers and needle-like leaves.
• Native — Symphyotrichum pilosum (frost aster) typically has smaller white flowers and more densely hairy stems and leaves.
• Native — Symphyotrichum novae-angliae (New England aster) has larger purple flowers and distinctly clasping, hairy leaves. Based on family patterns:
• Native — Eurybia species (formerly Aster) can be distinguished by their broader, more heart-shaped basal leaves and typically earlier bloom times.
Wikipedia Summary:
Symphyotrichum oolentangiense or Aster azureus (common name skyblue aster or azure aster) is a species of flowering plant in the daisy family Asteraceae, native to North American Atlantic Region.
Cloudinary Images - Identification
3 images
